‘In a crowd, it feels good when we do bad to our enemies’: how anger becomes contagious Negative emotions, particularly anger, become highly contagious in group settings, overriding individual rationality and fostering a sense of belonging and empowerment. This phenomenon, observed in historical events and modern online interactions, can drive collective action for social change, but also be exploited for division. Understanding this ‘moral contagion’ is key to navigating the complexities of group psychology and its impact on behavior.

• Individual anger is typically mitigated, but in groups, negative emotions intensify and spread like contagion.
• Historical examples like the MayDay 2K protests and the Paris Commune illustrate how group emotions can lead to uncharacteristic and extreme behaviors.
• Online environments, through anonymity and group dynamics, can amplify anger and negative emotions, similar to real-world crowds.
• Collective emotional experiences can provide a sense of identity, belonging, and empowerment, making even negative emotions feel rewarding in a group context.
• While collective anger can be a powerful tool for social change and cohesion, it can also be manipulated by ‘angertainment’ to create division.
• The contagious nature of anger, particularly ‘moral anger’, is more potent than other emotions and can lead to collective action or destructive behavior.